Quantification of the spin-Hall anti-damping torque with a resonance spectrometer

TL;DR

This paper introduces a cavity-based resonance spectrometer technique to measure the spin Hall anti-damping torque in bilayer materials, providing a simple and sensitive method applicable to low-conductivity systems.

Contribution

The study demonstrates a novel, straightforward approach to quantify spin Hall effects using resonance spectroscopy, independent of magnetic layer thickness.

Findings

Effective spin Hall angle of 0.08-0.09 measured

Technique applicable to low-conductivity and low-magnetoresistance materials

Resonance spectrometer can be a versatile tool for spin Hall studies

Abstract

We present a simple technique using a cavity-based resonance spectrometer to quantify the anti-damping torque due to the spin Hall effect. Modification of ferromagnetic resonance is observed as a function of small DC current in sub-mm-wide strips of bilayers, consisting of magnetically soft FeGaB and strong spin-Hall metal Ta. From the detected current-induced linewidth change, we obtain an effective spin Hall angle of 0.08-0.09 independent of the magnetic layer thickness. Our results demonstrate that a sensitive resonance spectrometer can be a general tool to investigate spin Hall effects in various material systems, even those with vanishingly low conductivity and magnetoresistance.